/**
 *  使用两个线程来累加 count 的值.
 *  每个线程循环 1w 次，累加变量 count 的值，count 默认值为 0，注意线程安全问题
 */

class Counter {
    public int count = 0;

    public synchronized void increase() {
        count++;
    }
}

public class TestDemo {
    public static void main(String[] args) throws InterruptedException {

        Counter counter = new Counter();

        Thread t1 = new Thread(() -> {
            for (int i = 0; i < 10000; i++) {
                counter.increase();
            }
        });
        Thread t2 = new Thread(() -> {
            for (int i = 0; i < 10000; i++) {
                counter.increase();
            }
        });
        t1.start();
        t2.start();

        t1.join();
        t2.join();

        System.out.println("count: " + counter.count);
    }
}
